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Endesa - Electricity, Gas, People

Heating and air conditioning in cars: how much petrol do they consume?

Published on July 5, 2019

Heating and air conditioning in petrol cars have completely different functions. However, everything changes if we're talking about electric cars. We’ll calculate your out-of-pocket expenses.

Today, it’s difficult for us to imagine a trip in a car without heating or air conditioning, depending on the season of the year. But for half of their history, cars didn’t have either one.

It was only after 1940 that some models started to emerge that were capable of controlling the interior cooling/heating. It is still possible to find cars that, in their basic versions, do not include air conditioning.

But how much petrol does it consume to use the heating or air conditioning in your car?

Car heating is free

Though many people don't know it, turning on the heat does not increase the car’s consumption of petrol.

Heat is obtained from the energy generated by the engine itself, and so it is enough to have it turned on to provide heat. For that reason, if you turn on the heat, you just need to wait a few minutes to feel its effects (however long it takes for the engine to heat up).

However, it is false to say that its consumption is equal to zero. The fan that makes the heat pass inside the car uses electricity from the battery. And to charge the battery, it also uses some petrol, but very little.

By taking advantage of the heat dissipation from the engine, heating a car is practically free

Air conditioning: up to 1 litre per 100 km

Air conditioning, on the other hand, uses a compressor connected to the belt of the engine in order to function. This consumes energy, and therefore, petrol. It consumes between approximately 0.2 litres and 1 litre of petrol per each 100 km.

Obviously, consuming more or less depends on both the exterior temperature and the intensity at which you use the air conditioning. The machine needs to cool the air inside the car: the more degrees it needs to go down, the more petrol it will consume.

Air conditioning of a car consumes between 0.2 and 1 litre of petrol at 100 km

Electrical cars: less dissipation, more sustainability

Everything changes with electric cars. A thermal motor wastes most of the heat it generates. As we’ve seen, this wasted part is what provides the heat in a petrol car.

However, an electric car strives not to waste anything. For that reason, if you turn on the heat, (in the case of electric cars) the consumption of energy will go up considerably.

Thus, we're talking about a paradigm shift. By driving a petrol car, you are wasting every metre you travel... and a side effect of this is that you can obtain heating based on that waste. But it is false to say that heating is free. It comes from the petrol that you're wasting.

By commuting in an electric car, everything is more controlled. When the car stops, energy consumption stops as well. Unless you need to use the lights, radio, or heating and air conditioning. The idea here is to always consume as little as possible, striving for zero waste.

If you drive an electric car and you need air conditioning or heat, the energy necessary will be extracted directly from the traction battery. You’ll have your cold/heat, but in turn, the autonomy of the vehicle will be reduced. How much? In normal conditions, it is around 10% or 20%.

To solve it, manufacturers are already implementing in their electric models, a small heat pump. This invention that is so common in homes and offices is thus carving out its niche in the future of driving by guaranteeing the maximum performance in any weather condition.

In electric cars, both air conditioning and heating consume energy of the battery, and therefore, reduce autonomy